Mazanderani (مازندرانی) or Tabari (طبری) is an Iranian language of the Northwestern branch, spoken mainly in Iran's Mazandaran, Tehran and Golestan provinces. As a member of the Northwestern branch (the northern branch of Western Iranian), etymologically speaking it is rather closely related to Gilaki, and more distantly related to Persian, which belongs to the Southwestern branch. Mazandarani is closely related to Gilaki and the two dialects have similar vocabularies.